Fish coloration is when a fish has different colors on their body that can help them to survive in their environment. Just like how people wear different colored clothes to fit in or stand out in different places, fish use their colors to do the same thing.
Some fish have bright colors and patterns to help them to blend into their surroundings. For example, if a fish lives in a coral reef, it may have bright colors and patterns that match the coral and other creatures that live there. This helps the fish to blend in and not be seen by predators that might want to eat them.
Other fish have bright colors to stand out and warn predators that they are poisonous or dangerous. These fish are called "aposematic" fish. They might have bright colors like yellow or orange to show that they have toxins in their bodies that can make predators sick.
Some fish can also change their colors to help them hide or communicate with each other. For example, a fish called a "chameleon fish" can change its color to match its surroundings. This helps it to blend in and not be seen by predators.
Overall, fish coloration is an important thing to help fish survive in their environment. They use their colors to blend in, stand out, warn predators, communicate with each other, and even to attract mates. It's like a big fish fashion show, but for survival!